The invention relates to QoS (Quality of Service) based Cell Capacity Dimensioning, particularly for several Traffic Classes.
Operator networks are constantly growing in size. It is not uncommon for networks to encompass 10,000 cells (BTS). Due to the size of the network it is difficult to determine how many TRX (Transceivers) should be deployed in each cell. However, the accurate dimensioning is very important, as both over-dimensioning and under-dimensioning will have serious disadvantages. Over-dimensioning means that frequencies have to be planned for the TRX, thus putting additional constraints on the frequency planning process, which results in sub-optimal network quality. Further, costs are spent un-necessarily on purchasing and installing TRX. Under-dimensioning means that QoS targets will not be met, hence subscribers will obtain sub-standard service.
In the past only one traffic class (voice traffic) was supported in GSM networks. Thus only the QoS requirements of this voice service had to be considered when dimensioning cell capacity of cells in the network. The current method of dimensioning GSM cells is based on blocking rate of speech traffic only.
A QoS approach for the initial release of data services was ‘best-effort’. I.e. packet-switched data is only being sent when voice traffic allows their transmission. This means that no QoS targets are being set for packet based services. Hence only background and non-realtime services such as FTP, downloading e-mails or web-browsing are suitable applications for this service. For any realtime application such as video telephony this QoS approach is not suitable, as the required level of capacity can not be guaranteed. With the ‘best-effort’ approach the actual data throughput does vary from cell to cell as the amount of spare capacity for packet-switched traffic is not the same in every cell. Moreover, with packet traffic not being uniformly distributed throughout the network certain cells will have a higher capacity demand than others. As a consequence subscribers of packet-switched services experience different QoS levels depending on the cell there are attached to. This situation is highly undesirable both for the subscriber as he does not always gets the desired level of service and for the operator as it is not possible to offer services that require QoS guarantees.